Method of fluxing using fluxing compositions containing benzotriazoles

ABSTRACT

A method of fluxing a solder or a metal substrate uses a fluxing composition that comprises a fluxing agent, in which the fluxing agent is a benzotriazole or a benzotriazole adduct. The adduct contains a benzotriazole segment and a segment with a curable and polymerizable functionality.

This application is a divisional of pending U.S. patent application Ser.No. 11/265,577.

BACKGROUND OF THE INVENTION

This invention relates to fluxing compositions containing benzotriazolecompounds and their application in electronic packaging, particularlywithin no-flow underfill compositions and pre-applied wafer levelunderfill for flip-chip based semiconductor packages and electronicassemblies. These compositions also have application for refluxing thesolder during solder reflow prior to a capillary underfill process.

An increasingly important method for attaching an integrated circuitonto a substrate in semiconductor packaging operations is the so-calledflip-chip technology. In flip-chip technology, the active side of thesemiconductor die is bumped with metallic solder balls and flipped sothat the solder balls can be aligned and placed in contact withcorresponding electrical terminals on the substrate. Electricalconnection is realized when the solder is reflowed to form metallurgicaljoints with the substrates. The coefficients of thermal expansion (CTE)of the semiconductor die, solder, and substrate are dissimilar and thismismatch stresses the solder joints, which ultimately can lead tofailure of the semiconductor package.

Organic materials, often filled with organic or inorganic fillers orspacers, are used to underfill the gap between the die and the substrateto offset the CTE mismatch and to provide enforcement to the solderjoints. Such underfill materials can be applied through a capillaryeffect, by dispensing the material along the edges of the die-substrateassembly after solder reflow and letting the material flow into the gapbetween the die and substrate. The underfill is then cured, typically bythe application of heat.

In an alternative process, an underfill material is pre-applied onto asolder bumped semiconductor wafer, either through printing if thematerial is a paste, or through lamination if the material is a film.The wafer is singulated into dies and an individual die subsequentlybonded onto the substrate during solder reflow, typically with theassistance of temperature and pressure, which also cures the underfillmaterial.

In another process, known as no-flow, a substrate is pre-dispensed withan underfill material, a flip-chip is placed on top of the underfill,and, typically with the assistance of temperature and pressure, thesolder is reflowed to realize the interconnection between the die andsubstrate. These conditions may cure the underfill material, althoughsometimes an additional cure step is necessary. The reflow process istypically accomplished on thermal compression bonding equipment, withina time period that can be as short as a few seconds.

In all three of these underfill operations, the solder is fluxed eitherbefore or during the reflow operation to remove any metal oxidespresent, inasmuch the presence of metal oxides hinders reflow of thesolder, wetting of the substrate by the solder, and electricalconnection. For capillary flow operations, fluxing and removal of fluxresidues is conducted before the addition of the capillary flowunderfill. For the no-flow and pre-applied underfill operations, thefluxing agent typically is added to the underfill material.

Many current no-flow underfill resins are based on epoxy chemistry,which achieve solder fluxing by using carboxylic acids or anhydrides.Organic alcohols are sometimes used as accelerators, since they canreact with anhydrides to form carboxylic acids, which in turn flux thesolder. The carboxylic acids from the anhydrides are volatile during thethermal compression bonding process, and may cause corrosion of thesemiconductor packages.

Moreover, anhydride based fluxing agents are not suitable forchemistries that are sensitive to acidic species, such as, cyanate esterbased underfill resins. The more reactive anhydrides are too aggressive,causing the resin monomers and oligomers to advance, leading to shortresin pot life and voiding during curing. The voiding can negativelyimpact the interconnections between the solder balls and substrates,causing short circuits and joint failure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 show the fluxing of adducts 54 and 55 with the epoxy onNi/Au coupons.

SUMMARY OF THE INVENTION

This invention is a fluxing composition comprising a fluxing agent, inwhich the fluxing agent is a 2-(2-hydroxyphenyl)benzotriazole or a2-(2-hydroxyphenyl)benzotriazole or a 2-(2-hydroxyphenyl)benzotriazoleadduct.

2-(2-Hydroxyphenyl)benzotriazole has the structure

in which additional hydroxyl groups may be present in the 3, 4, 5, or6position of the 2-hydroxyphenyl ring, or may be linked to the2-hydroxyphenyl ring through an aliphatic group, such as in the compound3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol shown here:

which is available as a fine white powder from Ciba as Tinuvin R 600,later referred to Adduct 55.

2-(2-Hydroxyphenyl)benzotriazole adducts, for the purpose of thisspecification and the claims, are compounds that contain two chemistrysegments: (1) a 2-(2-hydroxyphenyl)benzotriazole segment, which maycontain additional hydroxyl groups in the 3,4, 5, or 6 position of the2-hydroxyphenyl ring, and (2) a segment that contains electron donor,electron acceptor, epoxy, or acetyl acetonate functionality.

As used herein, the word “benzotriazole” will be deemed to mean2-(2-hydroxyphenyl)benzotriazole compounds and2-(2-hydroxyphenyl)benzotriazole adducts.

The benzotriazole compounds and the benzotriazole segment of thebenzotriazole adducts are capable of chelation by the formation of a6-membered ring with a metallic substrate as illustrated here:

These compounds are also weakly acidic through deprotonation of thephenolic hydroxyl. Both of these properties make them suitable fluxingagents with chemistries that are sensitive to acid.

In those cases where the fluxing agent is the benzotriazole adduct, theelectron donor, electron acceptor, or epoxy functionality segment iscapable of reacting with the underfill resin to immobilize thebenzotriazole, which prevents it from causing voiding during the curecycle. If acetyl acetonate functionality is present, it performs as anadhesion promoter to metal surfaces, such as solder bumps.

DETAILED DESCRIPTION OF THE INVENTION

In one embodiment, the benzotriazole used in the fluxing compositionwill have the structures of the 2-(2-hydroxyphenyl)benzotriazolecompounds as described earlier.

In a further embodiment, the benzotriazole fluxing agent used in thefluxing composition will be a benzotriazole adduct having the structure:

in which n is 0, 1, 2, or 3;E and E′ independently are an organic moietycontaining electron donor, electron acceptor, epoxy, or acetyl acetonatefunctionality; Z is hydrogen, hydrocarbyl, or an organic moietycontaining electron donor, electron acceptor, epoxy, or acetyl acetonatefunctionality; Z′ is hydrogen, hydrocarbyl, an electron donating group(such as, —OCH₃, phenyl); an electron withdrawing group (such as —NO₂,—CN); and L and L′ independently are a direct bond, a hydrocarbyl group,or a functionality selected from the group consisting of.

in which R is a direct bond or a hydrocarbyl group attached to thebenzotriazole segment, and R′ is hydrogen, an aromatic, or an alkylgroup of 1 to 6 carbon atoms, and preferably is hydrogen, methyl orethyl.

Within this specification and claims, hydrocarbyl group means, forexample, a linear or branched alkyl or alkenyl group or a cyclic alkylor alkenyl group, or an aromatic group. An organic moiety containing anelectron donor, electron acceptor, epoxy, vinyl, or acetyl acetonatefunctionality, means that functionality itself, or that functionalitywith a hydrocarbyl group.

Exemplary electron donor groups are vinyl ethers, vinyl silanes,compounds containing carbon to carbon double bonds attached to anaromatic ring and conjugated with the unsaturation in the aromatic ring,such as compounds derived from cinnamyl and styrenic starting compounds.Exemplary electron acceptor groups are fumarates, maleates, acrylates,and maleimides.

In another embodiment the benzotriazole adduct will have the structure:

in which n, E, L, Z and Z′ are as described above and at least one of Zand Z′ cannot be hydrogen or alkyl.

The electron donor, electron acceptor, epoxy or acetyl acetonatefunctionality can be attached to the benzotriazole segment through the2-hydroxyphenyl ring, through the 2-hydroxyl group itself, or throughthe benzyl ring of the benzotriazole.

In addition to the electron donor, electron acceptor, epoxy, or acetylacetonate functionality, the 2-hydroxyphenyl ring may also contain asecond organic moiety having a reactive functionality.

An exemplary benzotriazole adduct is2-(3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl) ethyl methacrylate,(hereinafter Compound B), which is a fine white powder commerciallyavailable from Ciba as Tinuvin R 796.

The benzotriazole adduct compounds of this invention, and otherbenzotriazole adducts having polymerizable segments positioned as the E,E′, Z or Z′ groups in the above structures, are suitable fluxing agentsfor underfill or fluxing compositions. The amount used in a formulationwill be an effective amount to promote fluxing and in general, aneffective amount will range from 0.005 to 20.0 percent by weight of theformulation. In addition, such fluxing compositions will contain acurable resin, optionally a curing initiator, and optionally conductiveor nonconductive filler.

In one embodiment, the fluxing composition can be used to flux soldersin a capillary underfill operation as described in the Backgroundsection of this specification. In that case, the fluxing compositionwill comprise a fluxing agent or a combination of several fluxingagents, a solvent or a combination of several solvents, and optionaladditives, such as dispersing agents and defoamers.

When used in a capillary flow operation, the thermal stability of thefluxing agent should be sufficient to withstand the elevated temperatureat which the solder is reflowed. The solder reflow temperature willdepend on the solder composition, and will vary with the actualmetallurgy. The practitioner will be able to make the determination ofthe solder reflow temperature by heating the solder until it reflows.The determination of the thermal stability of the fluxing agent can bereadily assessed by thermal gravimetric analysis (TGA), a technique wellwithin the expertise of one skilled in the art.

In another embodiment, the fluxing composition of this inventioncomprises one or more resins; optionally, one or more curing agents forthose resins; and optionally conductive or nonconductive fillers. Thecurable resin will be present in an amount from 10 to 99.5 weight %; thecuring agent, if present, will be present in an amount up to 30 weight%; the fillers, if present, will be present in an amount up to 80 weight%; and the fluxing agent will be present in an amount from 0.5 to 30weight %.

Suitable resins for the fluxing composition include, but are not limitedto, epoxy, electron donor resins (such as, vinyl ethers, vinyl silanes,thiolenes, and resins that contain carbon to carbon double bondsattached to an aromatic ring and conjugated with the unsaturation in thearomatic ring, such as compounds derived from cinnamyl and styrenicstarting compounds), and, electron acceptor resins (such as, fumarates,maleates, acrylates, and maleimides), polyamide, phenoxy,polybenzoxazine, cyanate ester, bismaleimide, polyether sulfone,polyimide, benzoxazine, siliconized olefin, polyolefin, polybenzoxyzole,polyester, polystyrene, polycarbonate, polypropylene, poly(vinylchloride), polyisobutylene, polyacrylonitrile, poly(methylmethacrylate), poly(vinyl acetate), poly(2-vinylpyridine),cis-1,4-polyisoprene, 3,4-polychloroprene, vinyl copolymer,poly(ethylene oxide), poly(ethylene glycol), polyformaldehyde,polyacetaldehyde, poly(b-propiolacetone), poly(10-decanoate),poly(ethylene terephthalate), polycaprolactam, poly(11-undecanoamide),poly(m-phenylene-terephthalamide),poly(tetramethlyene-m-benzenesulfonamide), polyester polyarylate,poly(phenylene oxide), poly(phenylene sulfide), polysulfone,polyetherketone, polyetherimide, fluorinated polyimide, polyimidesiloxane, polyisoindolo-quinazolinedione, polythioetherimide,polyphenylquinoxaline, polyquinixalone, imide-aryl etherphenylquinoxaline copolymer, polyquinoxaline, polybenzimidazole,polybenzoxazole, polynorbornene poly(arylene ethers), polysilane,parylene, benzocyclobutenes, hydroxy(benzoxazole) copolymer,poly(silarylene siloxanes), and polybenzimidazole.

In one embodiment, the resins include cyanate esters, epoxies,bismaleimides, (meth)acryates, and a combination of one or more ofthese.

Suitable curing agents are thermal initiators and photoinitiatorspresent in an effective amount to cure the fluxing composition. Ingeneral, those amounts will range from 0.5% to 30%, preferably 1% to20%, by weight of the total organic material (that is, excluding anyinorganic fillers) in the formulation. Preferred thermal initiatorsinclude peroxides, such as butyl peroctoates and dicumyl peroxide, andazo compounds, such as 2,2′-azobis(2-methyl-propanenitrile) and2,2′-azobis(2-methyl-butanenitrile). A preferred series ofphotoinitiators is one sold under the trademark Irgacure by CibaSpecialty Chemicals. In some formulations, both thermal initiation andphotoinitiation may be desirable: the curing process can be startedeither by irradiation, followed by heat, or can be started by heat,followed by irradiation.

In general, the formulations will cure within a temperature range of 70°C. to 250° C., and curing will be effected within a range of ten secondsto three hours. The actual cure profile will vary with the componentsand can be determined without undue experimentation by the practitioner.

Fluxing compositions typically comprise nonconductive fillers, such as,particles of vermiculite, mica, wollastonite, calcium carbonate,titania, sand, glass, fused silica, fumed silica, barium sulfate, andhalogenated ethylene polymers, such as tetrafluoroethylene,trifluoroethylene, vinylidene fluoride, vinyl fluoride, vinylidenechloride, and vinyl chloride. For some purposes, the fluxingcompositions may also comprise electrically or thermally conductivefillers, such as, carbon black, graphite, gold, silver, copper,platinum, palladium, nickel, aluminum, silicon carbide, boron nitride,diamond, and alumina. If present, fillers generally will be in amountsof 20% to 90% by weight of the formulation.

The following are synthetic procedures that can be used to makebenzotriazole adducts as disclosed in this specification. Theseprocedures, and exemplary adducts, have been previously disclosed inU.S. Pat. No. 6,930,136.

PROCEDURE 1. Reaction of isocyanate with alcohol. One mole equivalent ofisocyanate is solvated in toluene in a three-necked flask equipped witha mechanical stirrer, addition funnel and nitrogen inlet/outlet. Thereaction is placed under nitrogen and catalytic of dibutyltin dilaurateis added with stirring as the solution is heated to 60° C. The additionfunnel is charged with one mole equivalent of alcohol dissolved intoluene. This solution is added to the isocyanate solution over tenminutes, and the resulting mixture is heated for an additional threehours at 60° C. After the reaction is allowed to cool to roomtemperature, the solvent is removed in vacuo to give the product.

PROCEDURE 2. Reaction of isocyanate with amine. One mole equivalent ofisocyanate is solvated in toluene in a three-necked flask equipped witha mechanical stirrer, addition funnel and nitrogen inlet/outlet. Thereaction is placed under nitrogen and the solution heated to 60° C. Theaddition funnel is charged with one mole equivalent of amine in toluene,and this solution is added to the isocyanate solution over ten minutes.The resulting mixture is heated for an additional three hours at 60° C.,after which it is allowed to cool to room temperature. The solvent isremoved in vacuo to give the product.

PROCEDURE 3. Reaction of alkyl halide with amine or mercaptan. One moleequivalent of alkyl halide is solvated in THF in a three neck flaskequipped with a mechanical stirrer and addition funnel. The additionfunnel is charged with one mole equivalent of amine or mercaptan in THFand this solution is added to the alkyl halide solution over ten minutesat 0° C. The resulting mixture is stirred for 12 hours at roomtemperature, after which the solvent is removed in vacuo and ether andwater are added to the resulting material. The organic layer isextracted and dried over MgSO₄, and the solvent removed in vacuo to givethe product.

PROCEDURE 4. Reaction of alkyl halide with alcohol. One mole equivalentof alcohol, an excess amount of 50% NaOH, a catalytic amount oftetrabutyl ammonium hydrogen sulfate, and one mole equivalent of alkylhalide in toluene are stirred for five hours at 53° C., then for fivehours at 75° C. The reaction is allowed to cool to room temperature andthe organic layer extracted and washed with brine three times. Theisolated organic layer is dried over MgSO₄, filtered, and the solventremoved in vacuo to give the product.

PROCEDURE 5. Conversion of alcohol functionality to chloridefunctionality. The synthetic procedure is conducted according to E. W.Collington and A. I. Meyers, J. Org. Chem. 36, 3044 (1971). To a stirredmixture of one mole equivalent of alcohol and 1.1 mole equivalent ofs-collidine under nitrogen is added one equivalent of lithium chloridedissolved in a minimum amount of dry dimethylformamide. On cooling to 0°C., a suspension is formed and this is treated dropwise with 1.1 moleequivalent of methane-sulfonyl chloride. Stirring is continued at 0° C.for one to one and one-half hour, after which the pale yellow reactionmixture is poured over ice-water. The aqueous layer is extracted withcold ether/pentane (1:1) and the combined extracts are washedsuccessively with saturated copper nitrate solution. This is continueduntil no further intensification of the blue copper solution occurs,indicating complete removal of s-collidine. The organic extracts aredried over Na₂SO₄ and concentrated at room temperature, providing theproduct.

PROCEDURE 6. Reaction of amine with acid chloride. One equivalent ofamine and one equivalent of triethylamine are mixed in dry methylenechloride at 0° C. One equivalent of acid chloride dissolved in drymethylene chloride is added and the mixture allowed to react for fourhours. The solvent is evaporated and the crude product is purified bycolumn chromatography using a gradient of hexane/ethyl acetate to givethe product.

PROCEDURE 8. Reaction of alcohol with carboxylic acid. One moleequivalent of carboxylic acid, one mole equivalent of alcohol, and acatalytic amount of sulfuric acid are solvated with toluene in afour-necked flask fitted with a Dean Stark apparatus, mercurythermometer, mechanical stirrer, and an inlet/outlet tube. The reactionmixture is blanketed with nitrogen and the temperature raised to reflux(110° C.). Reflux is maintained for approximately four hours, at whichpoint water (indicating the reaction is progressing) is obtained in theDean Stark trap along with solvent. The condensate trap is emptied toremove the collected water and toluene and an amount of toluene equal tothe amount of water and toluene removed is charged to the flask tomaintain a consistent solvent level. Following another 30 minutes ofreflux, the trap is again emptied and the reaction flask recharged withfresh solvent to replace the distillate that is removed. This process isrepeated four more times to maximize water removal from the system.Following the final 30 minutes of reflux, the heat is removed, thesolvent is evaporated, and the crude product is purified by columnchromatography using a gradient of hexane/ethyl acetate to give theproduct.

PROCEDURE 9. Reaction of alcohol with vinyl silane. One mole equivalentof alcohol and triethylamine are mixed in dry toluene at 0° C., to whichis added one mole equivalent of vinyl silane dissolved in toluene. Themixture is allowed to react for four hours at room temperature, afterwhich the solvent is evaporated to give the product.

PROCEDURE 10. Reaction of isocyanate with mercaptan. One mole equivalentof isocyanate is solvated in toluene in a three-necked flask equippedwith a mechanical stirrer, addition funnel and nitrogen inlet/outlet.The reaction is placed under nitrogen and the solution heated to 60° C.The addition funnel is charged with one mole equivalent of mercaptan intoluene. This solution is added to the isocyanate solution over tenminutes, and the resulting mixture is heated for an additional threehours at 60° C. After the reaction is allowed to cool to roomtemperature, the solvent is removed in vacuo to give the product.

PROCEDURE 11. Reaction of isothiocyanate with alcohol. One moleequivalent of isothiocyanate is solvated in toluene in a three-neckedflask equipped with a mechanical stirrer, addition funnel and nitrogeninlet/outlet. The reaction is placed under nitrogen, and a catalyticamount of dibutyltin dilaurate is added with stirring as the solution isheated to 60° C. The addition funnel is charged with one mole equivalentof alcohol dissolved in toluene, which is added to the isothiocyanatesolution over ten minutes. The resulting mixture is heated for anadditional three hours at 60° C. After the reaction is allowed to coolto room temperature, the solvent is removed in vacuo to give theproduct.

PROCEDURE 13. Reaction of carboxylic acid with isocyanate. The synthesisis conducted according to T. Nishikubo, E. Takehara, and A. Kameyama,Polymer Journal, 25, 421 (1993). A stirred mixture of one moleequivalent of isocyanate and one mole equivalent of carboxylic acid issolvated in toluene in a three-necked flask equipped with a mechanicalstirrer and nitrogen inlet/outlet. The mixture is heated for two hoursat 80° C., and then allowed to cool to room temperature. The solventremoved in vacuo to give the product.

PROCEDURE 14. Reaction of disiloxane with vinyl epoxy. A round-bottomedflask is charged with one mole equivalent of disiloxane and one moleequivalent of vinyl epoxy resin. The reaction flask is equipped with amagnetic stirrer and a reflux condenser. To this mixture is added acatalytic amount of tris(triphenylphosphine)rhodium(I) chloride, and thereaction mixture is heated to 80-85° C. for six hours. The reaction isfollowed using gas chromatography by monitoring the disappearance of thestarting materials and the appearance of the products. After thecompletion of the reaction, pure product is obtained by fractionalvacuum distillation.

PROCEDURE 15. Synthesis of epoxy functional benzotriazole. One moleequivalent of benzotriazole is dissolved in toluene and placed in atwo-necked round bottomed flask. One mole equivalent of epoxy siloxaneadduct is added to the flask, and the reaction mixture is heated to 60°C. One drop of Karstedt's catalyst is added to initiate thehydrosilation reaction, which is monitored by following thedisappearance of Si-H band at 2117 cm⁻¹ in the infrared spectrum. Thereaction is over in approximately two to three hours After cooling, thereaction mixture is poured with stirring into methanol to precipitatethe product. The precipitated benzotriazole is washed with methanol anddried in vacuo at 60° C. for eight hours.

PROCEDURE 16. Reaction of phenol or acetoacetate with alkyl or alkenylhalide. One mole equivalent of phenol or acetoacetate is charged to athree-necked flask equipped with a mechanical stirrer, condenser, andinlet/outlet tube for nitrogen. Methyl ethyl ketone is added and thereaction placed under nitrogen gas. Alkyl or alkenyl halide is addedthrough a syringe and stirring initiated. Potassium carbonate is addedand the reaction mixture heated at 50° C. for 11 hours, allowed to coolto room temperature, and vacuum filtered. The filtrate is washed with 5%NaOH and 10% Na₂SO₄. The organic layer is dried over MgSO₄, and thesolvent evaporated off to give the product.

PROCEDURE 17. Reaction of alcohol or amine with diketene. Alcohol oramine, and acetone and triethylamine are added to a three-necked flaskequipped with an addition funnel and magnetic stirrer. The mixture iscooled to 0° C. and diketene in acetone is added to the addition funnelunder nitrogen. Diketene is added to the flask over approximately 30minutes, after which the reaction mixture is stirred at room temperaturefor five hours. The solvent is removed under reduced pressure and thesolid product is ground with mortar and pestle and washed with water ina beaker. The mixture is vacuum filtered and the solid is washed withhexane. This product is placed in an aluminum pan and dried in a vacuumoven to give the product.

PROCEDURE 18. Reaction of phenol with epoxy. An agitated mixture of onemole equivalent of epoxy resin, one mole equivalent of phenolic resin,and 0.4 mole equivalent of tetramethylammonium chloride is heated to 85°C., and maintained at this temperature for a period of 12 hours. Uponbeing cooled to room temperature, the resulting reaction productpartially solidified. The resulting material is recrystallized frommethanol-water solution to give the product.

PROCEDURE 19. Reaction of carboxylic acid with epoxy. An agitatedmixture of one mole equivalent of epoxy resin, one mole equivalent ofcarboxylic acid resin, and 0.4 mole equivalent of tetramethylammoniumbromide is heated to 80° c., and maintained at this temperature, for aperiod of 10 hours. Upon being cooled to room temperature, the resultingreaction product, which is in the form of a viscous oil, is removed andsubjected to a base titration. The resulting material is recrystallizedfrom methanol-water solution to give the product

PROCEDURE 20. Reaction of benzotriazole with alcohol. In a round-bottleflask, one mole equivalent of benzotriazole and one mole equivalent ofalcohol are dissloved in 97% sulfuric acid and stirred using aTeflon-coated magnetic stirring bar during 20 hours. The flask is cooledwith ice for the first two hours, after which the solution is allowed tocome to room temperature. At the end of the reaction, the solution ispoured into ice and water to precipitate the product. The suspension isfiltered, and the collected crude product washed with water and dried.The crude product is recrystallized from a 1:1 mixture of ethanol-ethylacetate.

The following are exemplary benzotriazole adducts and synthetic methodsfor obtaining those compounds.

3-Isopropenyl-α,α-dimethylbenzyl isocyanate (TMI, m-30.0 g, 0.149 mole)was solvated in 50 mL toluene in a 500 mL three-necked flask equippedwith a mechanical stirrer, addition funnel and nitrogen inlet/outlet.The reaction was placed under nitrogen, and 0.01 equivalent catalyticdibutyltin dilaurate was added with stirring as the solution heated to70° C. The addition funnel was charged with3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol (38.1 g, 0.149mole) dissolved in 50 mL toluene and this was added to the isocyanatesolution over ten minutes. The resulting mixture was heated for anadditional three hours at 70° C. After the reaction was allowed to coolto room temperature, the mixture was washed with distilled water threetimes. The isolated organic layer was dried over MgSO₄, filtered, andthe solvent removed in vacuo to give the product in 97% yield.

A solution of one mole equivalent of maleic anhydride in acetonitrilewas added to a one mole equivalent of 6-aminocaprioc acid in aceticacid. The mixture was allowed to react for three hours at roomtemperature. The formed white crystals were filtered off, washed withcold acetonitrile and dried to produce the amic acid adduct. The amicacid adduct was mixed with triethylamine in toluene, the mixture heatedto 130° C. for two hours and the water of reaction collected in aDean-Stark trap. The organic solvent was evaporated and 2M HCL added toreach pH 2. The product was extracted with ethyl acetate, and the ethylacetate solution was dried over MgSO₄. The solvent was evaporated togive 6-maleimidocaproic acid (MCA).

6-Maleimidocaproic acid (MCA, 18.17 g, 0.0861 mole),3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol (20.0 g, 0.0783mole) and 250 mL toluene were added to a 500 mL three-necked flask andheated to 80° C. until solids were dissolved. Sulfuric acid catalyst(0.384 g) was added and the heat was increased to 140° C. After 11 hoursof heating, the water of reaction (1.41 mL) and toluene (25 mL) wereremoved from Dean-Stark apparatus. Fresh toluene (25 mL) was replaced inthe flask. This was repeated three times to maximize water removal fromthe system. Triethyl amine (7.80 mL) was added and the mixture wasallowed to stir for one hour at room temperature. NaCl (20%) was addedto the mixture and the mixture transfered to a separatory funnel. Theorganic layer was isolated and dried over MgSO₄ followed by evaporationof the solvent to give the product in 75% yield.

Adduct 1 (10 g, 0.0219 mole) and 80 mL methyl ethyl ketone were added toa 250 mL three-necked flask equipped with a mechanical stirrer andcondenser and placed under nitrogen gas. Allyl bromide (7.95 g, 0.066mole) was added to the flask through a syringe and stirring wasinitiated. Potassium carbonate was added to the flask and the reactionmixture was heated at 50° C. for 11 hours, after which it was allowed tocool to room temperature and vacuum filtered. The filtrate was washedwith 5% NaOH and 10% Na₂SO₄. The organic layer was dried over MgSO₄followed by evaporation of the solvent to give the product in 65% yield.

In a 500 mL three-necked flask equipped with an addition funnel andstirrer was added 3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol(46.72 g, 0.183 mole), 150 mL reagent grade acetone and triethylamine.The mixture was cooled to 0° C. Diketene (20 g, 0.238 mole) in 20 mLacetone was added to the addition funnel under nitrogen and added to theflask over approximately 30 minutes. The reaction mixture was stirred atroom temperature for 5 hours, after which the solvent was removed underreduced pressure. The solid product was ground with mortar and pestleand washed with water in a beaker. The mixture was vacuum filtered andthe solid washed with hexane. The product was placed in an aluminum panand dried in a vacuum oven to give the product in 85% yield.

Adduct 5 can be prepared according to Procedure 16 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol andepichlorohydrin, followed by reaction with diketene according toProcedure 17.

Adduct 6 can be prepared according to Procedure 16 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol andepichlorohydrin, followed by reaction with m-TMI according to procedure1.

Adduct 7 can be prepared according to Procedure 16 by the reaction of3(2H-benzotriazole-2-yl)-4-hydroxy-phenethyl alcohol and cinnamylchloride, followed by reaction with m-TMI according to Procedure 1.

Adduct 8 can be prepared according to Procedure 16 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxy-phenethyl alcohol and cinnamylchloride, followed by reaction with diketene according to Procedure 17.

Adduct 9 can be prepared according to Procedure 16 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxy-phenethyl alcohol and cinnamylchloride, followed by reaction with cinnamyl chloride according toProcedure 4.

Adduct 10 can be prepared according to Procedure 9 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol and trivinylchlorosilane.

Adduct 11 can be prepared according to Procedure 16 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxy-phenethyl alcohol (BzTz-OHPhEtOH)and cinnamyl chloride, followed by reaction with trivinyl chlorosilaneaccording to Procedure 9.

Adduct 12 can be prepared according to Procedure 1 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol and 4,4′methylenedi(phenylisocyanate (MDI), followed by reaction with cinnamyl alcoholaccording to Procedure 1.

Adduct 13 can be prepared according to Procedure 1 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol and 4,4′methylenedi(phenylisocyanate) (MDI), followed by reaction with cinnamyl amineaccording to Procedure 2.

Adduct 14 can be prepared according to Procedure 1 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol and 4,4′methylenedi(phenylisocyanate) (MDI), followed by reaction with glycidol accordingto Procedure 1.

Adduct 15 can be prepared according to Procedure 5 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol with methylsulfonyl chloride and lithium chloride, followed by reaction withcinnamyl alcohol according to Procedure 4.

Adduct 16 can be prepared according to Procedure 5 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol with methylsulfonyl chloride and lithium chloride, followed by reaction withhydroxybutyl vinyl ether according to Procedure 4.

Adduct 17 can be prepared according to Procedure 1 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol and 4,4′methylenedi(phenylisocyanate) (MDI), followed by reaction with hydroxybutyl vinylether according to Procedure 1.

Adduct 18 can be prepared according to Procedure 5 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol with methylsulfonyl chloride and lithium chloride, followed by reaction with allylalcohol according to Procedure 4.

Adduct 19 can be prepared according to Procedure 14 by the reaction of3-vinyl-7-oxabicyclo[4.1.0]heptane with 1,1,3,3-tetramethyl-disiloxaneto give1-[2-(3[7-oxabicyclo[4.1.0]heptyl])ethyl]-1,1,3,3-tetramethyl-disiloxane,then by the reaction of the benzotriazole adduct 23 according toProcedure 15.

Adduct 20 can be prepared according to Procedure 1 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol with 4,4′methylenedi(phenylisocyanate) (MDI), followed by reaction with 6-maleimidocaproicacid (synthesis described in Adduct 2) according to Procedure 13.

Adduct 21 can be prepared according to Procedure 5 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol with methylsulfonyl chloride and lithium chloride, followed by reaction withammonia according to Procedure 3. The product, which is a primary amine,is reacted with cinnamyl chloride according to Procedure 3.

Adduct 22 can be prepared according to Procedure 5 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol with methylsulfonyl chloride and lithium chloride, followed by reaction withammonia according to Procedure 3. The product, which is a primary amine,is reacted with 6-maleimidocaproic acid chloride (prepared from6-maleimidocaproic acid and thionyl chloride according to Procedure 6)according to Procedure 3. See FIG. 1.

Adduct 23 can be prepared according to Procedure 5 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol with methylsulfonyl chloride and lithium chloride, followed by reaction withammonia according to Procedure 3. The product, which is a primary amine,is reacted with m-TMI according to Procedure 2.

Adduct 24 can be prepared according to Procedure 5 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol with methylsulfonyl chloride and lithium chloride, followed by reaction withammonia according to Procedure 3. The product, which is a primary amine,is reacted with chloroethyl vinyl ether according to Procedure 3.

Adduct 25 can be prepared according to Procedure 5 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol with methylsulfonyl chloride and lithium chloride, followed by reaction withammonia according to Procedure 3. The product, which is a primary amine,is reacted with diketene according to Procedure 17.

Adduct 26 can be prepared according to Procedure 18 by the reaction of2-(2,4-dihydroxyphenyl) benzotriazole with[(4-ethenylphenoxy)-methyl]-oxirane.

Adduct 27 prepared according to Procedure 18 by the reaction of5-hydoxy-2-(hydroxyphenyl) benzotriazole with [(4-ethenyl-phenoxy)methyl]-oxirane.

Adduct 28 can be prepared according to Procedure 19 by the reaction of2-(5-carboxy-2-hydrophenyl) benzotriazole with [(4-ethenyl-phenoxy)methyl]-oxirane.

Adduct 29 can be prepared according to Procedure 19 by the reaction of5-carboxy-2-(5-methyl-2-hydroxyphenyl) benzotriazole with[(4-ethenylphenoxy)methyl]-oxirane.

Adduct 30 can be prepared according to Procedure 13 by the reaction of5-carboxy-2-(5-methyl-2-hydroxyphenyl) benzotriazole with m-TMI.

Adduct 31 can be prepared according to Procedure 13 by the reaction of2-(5-carboxy-2-hydrophenyl) benzotriazole with m-TMI.

Adduct 32 can be prepared according to Procedure 16 by the reaction of2-(2,4-dihydroxyphenyl) benzotriazole with cinnamyl chloride.

Adduct 33 can be prepared according to Procedure 16 by the reaction of5-hydroxy-2-(hydroxyphenyl) benzotriazole with cinnamyl chloride.

Adduct 34 can be prepared according to Procedure 16 by the reaction of5-hydoxy-2-(hydroxyphenyl) benzotriazole with epichlorohydrin.

Adduct 35 can be prepared according to Procedure 16 by the of2-(2,4-dihydroxyphenyl) benzotriazole with epichlorohydrin.

Adduct 36 can be prepared according to Procedure 8 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol and fumaric acidethyl ester.

Adduct 37 can be prepared according to Procedure 8 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol with mercaptoaceticacid, followed by reaction with m-TMI according to Procedure 10.

Adduct 38 can be prepared according to Procedure 8 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol with mercaptoaceticacid, followed by reaction with cinnamyl chloride according to Procedure3.

Adduct 39 can be prepared according to Procedure 5 by the reaction of3-(2H-benzotriazole-2-yl)-4-hydroxyphenethyl alcohol with methylsulfonyl chloride and lithium chloride, followed by reaction withammonia according to Procedure 3. The product, which is a primary amine,is reacted with allylisothiocyanate according to Procedure 11.

Adduct 40 can be prepared according to Procedure 8 by the reaction of2-[2-hydroxy-5-(2-carboxyethyl)phenyl]-2H-benzotriazole (preparedaccording to L. Stoeber, A. Sustic, W. J. Simonsick, and O. Vogl,J.M.S.-Pure Appl. Chem., A37(9), 943, 2000) with cinnamyl alcohol.

Adduct 41 can be prepared according to Procedure 8 by the reaction of2-[2-hydroxy-5-(2-carboxyethyl)phenyl]-2H-benzotriazole (preparedaccording to L. Stoeber, A. Sustic, W. J. Simonsick, and O. Vogl,J.M.S.-Pure Appl. Chem., A37(9), 943, 2000) with N-methylolmaleimide(prepared according to J. Bartus, W. L. Simonsick, and O. Vogl,J.M.S.-Pure Appl. Chem., A36(3), 355, 1999).

Adduct 42 can be prepared according to Procedure 13 by the reaction of2-[2-hydroxy-5-(2-carboxyethyl)phenyl]-2H-benzotriazole (preparedaccording to L. Stoeber, A. Sustic, W. J. Simonsick, and O. Vogl,J.M.S.-Pure Appl. Chem., A37(9), 943, 2000) with m-TMI.

Adduct 43 can be prepared according to Procedure 20 by the reaction of2-[2-hydroxy-5-(2-carboxyethyl)phenyl]-2H-benzotriazole (preparedaccording to L. Stoeber, A. Sustic, W. J. Simonsick, and O. Vogl,J.M.S.-Pure Appl. Chem., A37(9), 943, 2000) with cinnamyl alcohol,followed by reaction with another molecule of cinnamyl alchoholaccording to Procedure 8.

Adduct 44 can be prepared according to Procedure 20 by the reaction of2-[2-hydroxy-5-(2-carboxyethyl)phenyl]-2H-benzotriazole (preparedaccording to L. Stoeber, A. Sustic, W. J. Simonsick, and O. Vogl,J.M.S.-Pure Appl. Chem., A37(9), 943, 2000) with cinnamyl alcohol,followed by reaction with m-TMI according to Procedure 13.

Adduct 45 can be prepared according to Procedure 20 by the reaction of2-[2-hydroxy-5-(2-carboxyethyl)phenyl]-2H-benzotriazole (preparedaccording to L. Stoeber, A. Sustic, W. J. Simonsick, and O. Vogl,J.M.S.-Pure Appl. Chem., A37(9), 943, 2000) with N-methylolmaleimide,followed by reaction with m-TMI according to Procedure 13.

Adduct 46 can be prepared according to Procedure 20 by the reaction of2-[2-hydroxy-5-(2-carboxyethyl) phenyl]-2H-benzotriazole (preparedaccording to L. Stoeber, A. Sustic, W. J. Simonsick, and O. Vogl,J.M.S.-Pure Appl. Chem., A37(9), 943, 2000) with N-methylolmaleimide,followed by reaction with cinnamyl alcohol according to Procedure 8.

Adduct 47 can be prepared according to Procedure 20 by the reaction of2-[2-hydroxy-5-(2-carboxyethyl) phenyl]-2H-benzotriazole (preparedaccording to L. Stoeber, A Sustic, W. J. Simonsick, and O. Vogl,J.M.S.-Pure Appl. Chem., A37(9), 943, 2000) with N-methylolmaleimide,followed by reaction with another molecule of N-methylolmaleimideaccording to Procedure 8.

Adduct 48 can be prepared according to Procedure 16 by the reaction of2-(2,4,6-trihydroxyphenyl)-1,3-di-(2H-benzotriazole) (prepared accordingto S. Li and O. Vogl, Ploymer Bulletin, 12, 375, 1984) with cinnamylchloride.

Adduct 49 can be prepared according to Procedure 16 by the reaction of2-(2,4,6-trihydroxyphenyl)-1,3-di-(2H-benzotriazole) (prepared accordingto S. Li and O. Vogl, Ploymer Bulletin, 12, 375, 1984) with cinnamylchloride.

Adduct 50 can be prepared according to Procedure 16 by the reaction of2-(2,4,6-trihydroxyphenyl)-1,3-di-(2H-benzotriazole) (prepared accordingto S. Li and O. Vogl, Ploymer Bulletin, 12, 375, 1984) withepichlorohydrin.

Adduct 51 can be prepared according to Procedure 16 by the reaction of2-(2,4,6-trihydroxyphenyl)-1,3-di-(2H-benzotriazole) (prepared accordingto S. Li and O. Vogl, Ploymer Bulletin, 12, 375, 1984) withepiclorohydrin.

Adduct 52 can be prepared according to Procedure 20 by the reaction of2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole with cinnamyl alcohol.

Adduct 53 was prepared as follows: A 250 mL 4-neck round-ottom flask wasequipped with a mechanical stirrer, reflux condenser, Dean Stark trap,and slow-addition funnel. The flask was charged with the di-acid havingthe structure

(6.2 g, 0.0222 mol), 3-(2H-benzotri-azole-2-yl)-4-hydroxyphenethylalcohol (11.32 g, 0.0444 mol), p-toluene sulfonic acid monohydrate (0.43g, 0.0022 mol) and toluene (50 mL). The slow-addition funnel was filledwith 125 mL additional toluene and mounted on the flask. With mixing,the charged reaction flask was placed in an oil bath preheated to 140°C. After three minutes, the thick reaction mixture changed to a darkbrown solution and within ten minutes of heating, solvent starteddistilling into the Dean-Stark trap. Over the course of five hours ofrefluxing, the trap was emptied five times and each time 25 mL of freshtoluene was charged to the flask. During this time, light colored solidsprecipitated from the reaction solution, eventually forming a lightyellow slurry. Extra toluene was added periodically to maintainrefluxing as the reaction mixture grew thicker. Following the five hoursof refluxing, the reaction was stopped and the solids were filtered fromthe mix and collected. Acetone (250 mL) was then combined with thesolids in a reaction flask and the resulting mixture was stirredmechanically for 30 minutes. Once again, the solids were filtered fromthe mix and collected. The acetone wash was repeated twice more. By thefinal wash, the acetone filtrate had changed from hazy gold to a clearand colorless solution. The resulting ivory white solids were thenrinsed with hexane, collected by filtration and dried over night in avacuum oven at 70° C. The structure and purity of thistransesterification adduct was confirmed by ¹H NMR. The ivory whitegranules were obtained in 65% yield.

Adduct 54, 2-(3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl) ethylmethacrylate, is commercially available from Ciba as Tinuvin R 796.

Adduct 55, 3-(2H-benzotri-azole-2-yl)-4-hydroxyphenethyl alcohol, iscommercially available from Ciba as Tinuvin R 600

PERFORMANCE EXAMPLE. In this example, Adducts 2, 54, and 55 were testedfor performance as fluxes applied directly to solder, as would be doneprior to a capillary flow operation. Performance was measured as theability of the fluxing agent to collapse a solder ball. Copper ornickel/gold-plated copper coupons were used as substrates and werepreheated on a hot plate to 240° C. (a temperature higher than themelting point of the solder). Five to ten mg of fluxing agent weredropped onto the heated hot plate, and then four to six granules ofsolder, enough to make a solder ball were dropped onto the fluxingagent. When a solder ball starts to flux, it rapidly collapses andmerges into a solder glob that displays a shiny surface. Adducts 54 and55 were tested on solder on copper coupons; adducts 54 and 55 also weretested with 10% by weight epoxy on solder on Ni/Au coupons; and adduct 2was tested on solder on nickel/gold coupons. The fluxing reaction wasobserved on all the examples tested and the time elapsed before thesolder ball collapsed was under 30 seconds in each case. FIGS. 1 and 2show the fluxing of adducts 54 and 55 with the epoxy on Ni/Au coupons.

1. A method of fluxing a solder or a metal substrate comprisingcontacting the solder or metal substrate with a composition comprising afluxing agent, in which the fluxing agent is a2-(2-hydroxyphenyl)benzotriazole or a 2-(2-hydroxyphenyl)-benzotriazoleadduct having the structure:

in which n is 0, 1, 2, or 3; E and E′ independently are an organicmoiety containing electron donor, epoxy, acetyl acetonate, or electronacceptor functionality; Z is hydrogen, hydrocarbyl, or an organic moietycontaining electron donor, epoxy, acetyl acetonate, or electron acceptorfunctionality; Z′ is hydrogen, hydrocarbyl, or an organic moietycontaining electron donating or electron withdrawing functionality; Land L′ independently are a direct bond, a hydrocarbyl group, or afunctionality selected from the group consisting of

in which R is a direct bond or a hydrocarbyl group attached to thebenzotriazole segment; and R′ is hydrogen, an aromatic, or an alkylgroup of 1 to 6 carbon atoms.
 2. The method according to claim 1 inwhich the fluxing agent is